Make EVP_CIPHER_CTX opaque and renew the creator / destructor functions

Following the method used for EVP_MD_CTX and HMAC_CTX,
EVP_CIPHER_CTX_init and EVP_CIPHER_CTX_cleanup are joined together
into one function, EVP_CIPHER_CTX_reset, with EVP_CIPHER_CTX_init kept
as an alias.
EVP_CIPHER_CTX_cleanup fills no purpose of its own any more and is
therefore removed.

Reviewed-by: Rich Salz <rsalz@openssl.org>

crypto/evp/evp_enc.c

@@ -66,17 +66,39 @@
 #endif
 #include "evp_locl.h"
 
-void EVP_CIPHER_CTX_init(EVP_CIPHER_CTX *ctx)
+int EVP_CIPHER_CTX_reset(EVP_CIPHER_CTX *c)
 {
-    memset(ctx, 0, sizeof(*ctx));
+    if (c == NULL)
+        return 1;
+    if (c->cipher != NULL) {
+        if (c->cipher->cleanup && !c->cipher->cleanup(c))
+            return 0;
+        /* Cleanse cipher context data */
+        if (c->cipher_data && c->cipher->ctx_size)
+            OPENSSL_cleanse(c->cipher_data, c->cipher->ctx_size);
+    }
+    OPENSSL_free(c->cipher_data);
+#ifndef OPENSSL_NO_ENGINE
+    if (c->engine)
+        /*
+         * The EVP_CIPHER we used belongs to an ENGINE, release the
+         * functional reference we held for this reason.
+         */
+        ENGINE_finish(c->engine);
+#endif
+    memset(c, 0, sizeof(*c));
+    return 1;
 }
 
 EVP_CIPHER_CTX *EVP_CIPHER_CTX_new(void)
 {
-    EVP_CIPHER_CTX *ctx = OPENSSL_malloc(sizeof(*ctx));
-    if (ctx != NULL)
-        EVP_CIPHER_CTX_init(ctx);
-    return ctx;
+    return OPENSSL_zalloc(sizeof(EVP_CIPHER_CTX));
+}
+
+void EVP_CIPHER_CTX_free(EVP_CIPHER_CTX *ctx)
+{
+    EVP_CIPHER_CTX_reset(ctx);
+    OPENSSL_free(ctx);
 }
 
 int EVP_CipherInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *cipher,
@@ -515,36 +537,6 @@ int EVP_DecryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl)
     return (1);
 }
 
-void EVP_CIPHER_CTX_free(EVP_CIPHER_CTX *ctx)
-{
-    EVP_CIPHER_CTX_cleanup(ctx);
-    OPENSSL_free(ctx);
-}
-
-int EVP_CIPHER_CTX_cleanup(EVP_CIPHER_CTX *c)
-{
-    if (!c)
-        return 0;
-    if (c->cipher != NULL) {
-        if (c->cipher->cleanup && !c->cipher->cleanup(c))
-            return 0;
-        /* Cleanse cipher context data */
-        if (c->cipher_data && c->cipher->ctx_size)
-            OPENSSL_cleanse(c->cipher_data, c->cipher->ctx_size);
-    }
-    OPENSSL_free(c->cipher_data);
-#ifndef OPENSSL_NO_ENGINE
-    if (c->engine)
-        /*
-         * The EVP_CIPHER we used belongs to an ENGINE, release the
-         * functional reference we held for this reason.
-         */
-        ENGINE_finish(c->engine);
-#endif
-    memset(c, 0, sizeof(*c));
-    return 1;
-}
-
 int EVP_CIPHER_CTX_set_key_length(EVP_CIPHER_CTX *c, int keylen)
 {
     if (c->cipher->flags & EVP_CIPH_CUSTOM_KEY_LENGTH)

crypto/evp/evp_locl.h

@@ -71,6 +71,26 @@ struct evp_md_ctx_st {
     int (*update) (EVP_MD_CTX *ctx, const void *data, size_t count);
 } /* EVP_MD_CTX */ ;
 
+struct evp_cipher_ctx_st {
+    const EVP_CIPHER *cipher;
+    ENGINE *engine;             /* functional reference if 'cipher' is
+                                 * ENGINE-provided */
+    int encrypt;                /* encrypt or decrypt */
+    int buf_len;                /* number we have left */
+    unsigned char oiv[EVP_MAX_IV_LENGTH]; /* original iv */
+    unsigned char iv[EVP_MAX_IV_LENGTH]; /* working iv */
+    unsigned char buf[EVP_MAX_BLOCK_LENGTH]; /* saved partial block */
+    int num;                    /* used by cfb/ofb/ctr mode */
+    /* FIXME: Should this even exist? It appears unused */
+    void *app_data;             /* application stuff */
+    int key_len;                /* May change for variable length cipher */
+    unsigned long flags;        /* Various flags */
+    void *cipher_data;          /* per EVP data */
+    int final_used;
+    int block_mask;
+    unsigned char final[EVP_MAX_BLOCK_LENGTH]; /* possible final block */
+} /* EVP_CIPHER_CTX */ ;
+
 /* Macros to code block cipher wrappers */
 
 /* Wrapper functions for each cipher mode */

include/openssl/evp.h

@@ -428,24 +428,6 @@ typedef struct evp_cipher_info_st {
     unsigned char iv[EVP_MAX_IV_LENGTH];
 } EVP_CIPHER_INFO;
 
-struct evp_cipher_ctx_st {
-    const EVP_CIPHER *cipher;
-    ENGINE *engine;             /* functional reference if 'cipher' is
-                                 * ENGINE-provided */
-    int encrypt;                /* encrypt or decrypt */
-    int buf_len;                /* number we have left */
-    unsigned char oiv[EVP_MAX_IV_LENGTH]; /* original iv */
-    unsigned char iv[EVP_MAX_IV_LENGTH]; /* working iv */
-    unsigned char buf[EVP_MAX_BLOCK_LENGTH]; /* saved partial block */
-    int num;                    /* used by cfb/ofb/ctr mode */
-    void *app_data;             /* application stuff */
-    int key_len;                /* May change for variable length cipher */
-    unsigned long flags;        /* Various flags */
-    void *cipher_data;          /* per EVP data */
-    int final_used;
-    int block_mask;
-    unsigned char final[EVP_MAX_BLOCK_LENGTH]; /* possible final block */
-} /* EVP_CIPHER_CTX */ ;
 
 /* Password based encryption function */
 typedef int (EVP_PBE_KEYGEN) (EVP_CIPHER_CTX *ctx, const char *pass,
@@ -703,10 +685,10 @@ int EVP_DecodeFinal(EVP_ENCODE_CTX *ctx, unsigned
                     char *out, int *outl);
 int EVP_DecodeBlock(unsigned char *t, const unsigned char *f, int n);
 
-void EVP_CIPHER_CTX_init(EVP_CIPHER_CTX *a);
-int EVP_CIPHER_CTX_cleanup(EVP_CIPHER_CTX *a);
 EVP_CIPHER_CTX *EVP_CIPHER_CTX_new(void);
-void EVP_CIPHER_CTX_free(EVP_CIPHER_CTX *a);
+int EVP_CIPHER_CTX_reset(EVP_CIPHER_CTX *c);
+void EVP_CIPHER_CTX_free(EVP_CIPHER_CTX *c);
+#define EVP_CIPHER_CTX_init(c) EVP_CIPHER_CTX_reset((c))
 int EVP_CIPHER_CTX_set_key_length(EVP_CIPHER_CTX *x, int keylen);
 int EVP_CIPHER_CTX_set_padding(EVP_CIPHER_CTX *c, int pad);
 int EVP_CIPHER_CTX_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg, void *ptr);